Carrier VAV Zone II Installation And Startup Manual page 72

Troubleshooting
To clean the flow sensor
You can use a can of compressed air to clean the sensors while the controller is installed or on a repair bench.
Disconnect the High and Low flow sensor tubes.
1
Insert the compressed air straw 1/4" into the controller's High connector.
2
WARNING The compressed air can MUST be upright. It will damage the flow sensors by producing ice
crystals if the can is on its side.
Press the air can's trigger twice for no more than 2 seconds each time.
3
Reconnect tubing to the High and Low flow sensor tubes.
4
VAV Zone II Controllers
Installation and Start-up Guide
68
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